Can annotations be used for code injection?

Question

I realise that this might be a question that has been asked and answered, but please bear with me.

I want to know if it is possible to use annotations to inject code int

Answer 1

You can do this, but you're not supposed to modify the class containing the annotations. (The trick you link to uses the compile tree api to modify the bytecode being generated...) This is not supported and will probably be guarded against in later Java SDKs.

The proper way to do it is to generate a superclass, subclass or wrapper class.

I've written a set of annotations that generate getters/setters and other fun stuff. I generate a superclass.

See http://code.google.com/p/javadude/wiki/Annotations

You can do things like

package sample;

import com.javadude.annotation.Bean;
import com.javadude.annotation.Property;
import com.javadude.annotation.PropertyKind;

@Bean(properties={
    @Property(name="name"),
    @Property(name="phone", bound=true),
    @Property(name="friend", type=Person.class, kind=PropertyKind.LIST)
}) 
public class Person extends PersonGen {
}

and it'll generate PersonGen for you with the fields/getters/setters and bound property support.